Collaborative Research: Frontiers in Xylem/Phloem Integration: The Influence of Transport Physiology on Photosynthesis, Growth and Drought Responses from Leaves to Ecosystems

Understanding the structure and function of the tissues that transport water and sugars in plants—xylem and phloem—is essential for predicting and managing the future of both agricultural and natural ecosystems and how they respond to stress. Yet, there are large gaps in current knowledge about how these tissues are organized, how they interact, and how they respond during drought. This project will test hypotheses for how the coordinated anatomy and physiology of leaf carbon and water transport determines the growth, drought resilience, and geographic distribution of plant species, for a wide range of species of herbs, shrubs, and trees from across the US. By combining measurements of xylem and phloem function with state-of-the-art mechanistic models at different scales (leaf, whole plant and ecosystem), the project team will generate fundamental discoveries and resolve how the leaf carbon and water transport systems contribute to whole plant and ecosystem function. This project will benefit the American public more broadly by creating unprecedented databases for leaf structure and function and plant responses to drought, by training undergraduate students in methods of research, data analysis, and writing, and—in collaboration with artists—by developing workshops to transform scientific research into creative public engagement, combining lectures, demonstrations, and hands-on activities, including creation of visual pieces and augmented- and virtual-reality experiences. Further, the project will include outreach to the grape and wine industry, highlighting new discoveries, as the interaction between sugar and water transport in grapevine leaves strongly influences grapevine stress responses and wine quality. The goal of this research is a mechanistic understanding of the variation in leaf xylem and phloem traits and their coordination and dynamics during drought, and implications at tissue, organ, plant and ecosystem levels. First, the project will break new ground in establishing how leaf sugar and water transport are integrated physiologically, and how this integration influences growth at leaf, plant, and ecosystem scales and adaptation across climatic niches. In particular, the project will resolve how leaf carbon and water transport anatomy and flow rates are coordinated within and across species, how they determine maximum rates of gas exchange and growth, how they vary with other functional traits, and how they adapt to environmental conditions. Second, the project will provide new resolution of drought impacts on leaf sugar and water transport across scales, including on ecosystem carbon and water fluxes. The project will clarify drought responses—how, and in what sequence, the sensitivities of the leaf xylem-phloem complex influence the responses and resilience of leaf gas exchange, leaf expansion, plant growth (and, if unrelieved, plant mortality), and ecosystem functions. The project team will generate physiological and functional trait data and model products that will be of value to a wide range of scientists from physiologists to ecologists, the training of many undergraduate and graduate students, innovative art/science workshops, and an unprecedented understanding of leaf xylem and phloem structure, dynamic transport, and implications for drought tolerance, adaptation and ecosystem function. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria. NSF Award ID: 2517068 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Matteo Detto | Institution: Princeton University, PRINCETON, NJ | Award Amount: $23,000 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2517068 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2517068.html